From 101acb51a8d63adc10e76027bc25503df8c55a1f Mon Sep 17 00:00:00 2001
Message-Id: <101acb51a8d63adc10e76027bc25503df8c55a1f.1715308075.git.mdw@distorted.org.uk>
From: Mark Wooding <mdw@chiark.greenend.org.uk>
Date: Sat, 13 Jul 2013 00:49:00 +0100
Subject: [PATCH] debian/tripe-peer-services.postinst: New script to restart
 services.
Organization: Straylight/Edgeware

From: Mark Wooding <mdw@distorted.org.uk>

When the TrIPE suite is upgraded, the service package isn't usually in a
fit state when the server is restarted, so the services don't start
properly.  The answer is to have the services restarted explicitly by
their own `postinst' script.
---
 Makefile.am                         |   1 +
 debian/tripe-peer-services.postinst | 100 ++++++++++++++++++++++++++++
 2 files changed, 101 insertions(+)
 create mode 100644 debian/tripe-peer-services.postinst

diff --git a/Makefile.am b/Makefile.am
index d86ec321..dbfa5121 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -137,6 +137,7 @@ EXTRA_DIST		+= debian/python-tripe.install
 
 ## peer services
 EXTRA_DIST		+= debian/tripe-peer-services.install
+EXTRA_DIST		+= debian/tripe-peer-services.postinst
 
 ## monitor
 EXTRA_DIST		+= debian/tripemon.install
diff --git a/debian/tripe-peer-services.postinst b/debian/tripe-peer-services.postinst
new file mode 100644
index 00000000..870ba1ae
--- /dev/null
+++ b/debian/tripe-peer-services.postinst
@@ -0,0 +1,100 @@
+#! /bin/sh -e
+
+silently () {
+  ## Run the command discarding all of its output.
+  "$@" >/dev/null 2>&1
+}
+
+restart_services () {
+  ## Restart the services we know about.
+
+  echo -n "Restarting services:"
+
+  ## Make sure that the server is actually running.
+  if ! silently tripectl version; then
+    echo " tripe server not running."
+    return 0
+  fi
+
+  ## Find out which of our services are actually configured to start.
+  ## We'll assume that a link to the service script is a good indication.
+  need_restart=$(perl -e '
+	  for my $svc (@ARGV) { $svc{$svc} = 1; }
+	  for my $link (</etc/tripe/services/*>) {
+	    next unless -l $link;
+	    my $targ = readlink $link;
+	    next unless defined $targ;
+	    next unless $targ =~
+	      m#/usr/lib/(?:[^/]+/)?tripe/services/([^/]+)#;
+	    next unless exists $svc{$1};
+	    print "$link\n";
+	  }' "$@")
+
+  ## If there's nothing to do then don't bother with the rest.
+  any=nil
+  for svc in $need_restart; do any=t; break; done
+  case $any in nil) echo " none configured."; return 0 ;; esac
+
+  ## Restart the services.  This is more than a little tricky.
+  for svc in $need_restart; do
+
+    ## Find out about the service.
+    set -- $("$svc" --version)
+    name="$1" version="$2"
+
+    ## Write some progress.
+    echo -n " $name"
+
+    ## If there's an instance of the service running already then we ask it
+    ## to quit.  This is where everything gets commplicated.
+    if silently tripectl svcensure "$name"; then
+
+      ## So, what we want to do is ask the service to quit, and make sure it
+      ## actually has done before starting the new version.  Conveniently,
+      ## the server emits a notification when a service quits.  Now all we
+      ## have to do is wait a reasonable time for the notification.
+      ##
+      ## So we read the output of tripectl(1).  Of course, to do this, we
+      ## must keep its standard input open, so we'll sleep for a bit.  We can
+      ## use this to implement our timeout.  The only problem is curtailing
+      ## the wait early if (as we expect) the service actually quits on time.
+      ## The answer is /very/ cheesy: we'll report the process-id of our
+      ## sleep(1) process through the server's notification mechanism.  Then,
+      ## when we see the `SVCRELEASE', we kill the sleep(1) and return
+      ## success.
+      if ! { echo "watch n"
+	     echo svcsubmit "$name" quit
+	     sleep 1& sleepkid=$!
+	     echo notify tripe-peer-services.postinst.$$ SLEEPKID=$sleepkid
+	     wait $sleepkid || :
+	   } |
+	   tripectl |
+	   { while read line; do
+	       case "$line" in
+		 "NOTE USER tripe-peer-services.postinst.$$ SLEEPKID="*)
+		   sleepkid=${line##*=}
+		   ;;
+		 "NOTE SVCRELEASE $name")
+		   kill $sleepkid
+		   exit 0
+		   ;;
+	       esac
+	     done; exit 1; }
+      then
+	echo -n " (STUCK)"
+	continue
+      fi
+    fi
+
+    ## Restart the service.  Pass `--startup' because (a) the server might
+    ## have started recently, and failed to start our services, and (b) our
+    ## services are (modulo some annoying warning messages) idempotent
+    ## anyway.
+    if ! "$svc" --daemon --startup; then echo -n " (FAILED)"; fi
+  done
+  echo "."
+}
+
+restart_services conntrack connect watch
+
+#DEBHELPER#
-- 
[mdw]